The incidence of congenital heart defects is 1 percent with 20 percent of these incidences corresponding to complex congenital lesions with only one effective pumping chamber; the latter are termed single ventricle heart defects. These statistics show that 2 babies out of every 1,000 births will be born with a single ventricle. Surgical treatment for these defects consists of bypassing the right side of the heart and connecting the systemic and pulmonary circulations in series with the univentricular pump. Patients who survive surgery require lifelong, intensive medical attention. Cardiologists report that the 20 percent of their caseload consisting of such patients requires over 50 percent of their time; this underscores the gravity of problems in patients as well as the need for improvements in existing treatment methods. The current surgical procedure of choice for patients with a single ventricle is the total cavopulmonary connection (TCPC). The central hypothesis for this Multi-Institutional BRP Project is that development of pre-operative computer-based surgical design methods will advance the state-of-the-art in clinical treatment of single-ventricle patients and improve their quality of life. The development of these methods will be guided by six specific aims: (i) development of baseline TCPC surgical templates based on fluid dynamic assessments of various TCPC configurations; (ii) study the impact of graft materials on local fluid dynamics following TCPC; (iii) compile anatomic and materials databases for validating computer-based surgical planning and design protocols; (iv) improve surgical planning and design through development of computer-based simulation tools facilitating prediction of potential post-operative flow conditions in any given patient; (v) investigate improvements in post-TCPC hemodynamics achieved by treating congenital abnormalities associated with the ascending aorta; (vi) determine the feasibility of reducing post-TCPC central venous pressure using a pressure regulator/pump.